staging: lustre: obdclass: obd_mount: Declare function as static

Declare lustre_mount() function static since it is defined and called in this
file only.

This fixes the following sparse warning:
drivers/staging/lustre/lustre/obdclass/obd_mount.c:1169:15: warning:
symbol 'lustre_mount' was not declared. Should it be static?
Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/obdclass/obd_mount.c

@@ -1163,7 +1163,7 @@ void lustre_register_kill_super_cb(void (*cfs)(struct super_block *sb))
 EXPORT_SYMBOL(lustre_register_kill_super_cb);
 
 /***************** FS registration ******************/
-struct dentry *lustre_mount(struct file_system_type *fs_type, int flags,
+static struct dentry *lustre_mount(struct file_system_type *fs_type, int flags,
 				const char *devname, void *data)
 {
 	struct lustre_mount_data2 lmd2 = {